The present invention relates to a press die that is used for forming, for example, a separator for a fuel cell.
Typically, separators used in fuel cells are formed by, as shown in FIG. 6, providing a plate 41 made of a hard material, such as titanium, with contiguous grooves and protrusions 42. The grooves and protrusions 42 define passages thorough which coolant or gas of hydrogen or oxygen flows.
When forming such a separator for a fuel cell, a press die apparatus as shown in FIG. 7 is conventionally used, for example. The press die apparatus includes a lower die 43 and an upper die 44. The lower die 43 has on the upper surface a die surface 431 with grooves and protrusions, and the upper die 44 has on the lower surface a die surface 441 on which grooves and protrusions are formed to correspond to the die surface 431 of the lower die 43. The upper die 44 is arranged above the lower die 43 to be brought toward and away from the lower die 43. With a plate 41, which is a workpiece, placed on the die surface 431 of the lower die 43, the upper die 44 is brought toward the lower die 43 to press the plate 41 between the die surfaces 431, 441 of the dies 43, 44, so that the grooves and protrusions 42 are formed on the plate 41.
When producing the lower die 43 and the upper die 44 of the press die apparatus, the surface of a die material is cut with a cutting tool to form the die surfaces 431, 441 having grooves and protrusions. In a case in which the die material is made of super hard metal, such as high-speed steel, the cutting tool easily becomes dull due to wear. Thus, it is difficult to form the die surfaces 431, 441 by cutting the die material at one stroke in a direction in which the grooves and protrusions extend on the die surfaces 431, 441 without replacing the cutting tool.
To deal with such a problem, a press die apparatus as illustrated in FIG. 8 has conventionally been proposed. The press die apparatus has a lower die 43 formed by die blocks 45, which are separate rectangular columns. The die blocks 45 are placed on a base 46 and fitted in a frame 47 such that the die blocks 45 are aligned. According to this configuration, limited parts of the end faces of the die blocks 45 are cut individually. Thus, the die surface 431 with grooves and protrusions can be easily formed by joining the cut surfaces. Although not illustrated, the upper die of the press die apparatus is configured by assembling die blocks as in the case of the lower die 43.
On the other hand, Japanese Laid-Open Patent Publication No. 11-33988 discloses press die apparatus that punches a workpiece using a punch and a die. The die is a split type and is supported on a die plate to be movable in a horizontal direction. Wedges for adjusting the position of the die in the horizontal direction are arranged on the die plate. The wedges are allowed to move in the vertical direction by adjuster screws. When the wedges are moved vertically by the adjuster screws, the die is moved horizontally by the wedge effect of the wedges so that the clearance between the punch and the die is adjusted. The die is then fixed to the adjusted position.